Aircraft wings are frequently provided with lift augmentation surfaces which, when extended, increase the lift produced by the wing at a given speed. This allows, for example, an aircraft to take off in a shorter distance or land at a slower speed.
One such lift augmentation surface is a wing leading edge slat. The slat is mounted at a leading edge of the wing and is selectively extended and retracted by means of a suitable actuator mechanism, for example a rack and pinion drive. Due to the size of the slat, the slat is typically moved by more than one actuator, for example by a pair of actuators, spaced apart along the span of the wing. The actuators are operated together to move the slat.
It is possible that in use one of the actuators may fail or become decoupled from the slat. The slat is relatively stiff, so the remaining actuator may still be able to move the slat. The disconnection of the actuator may not however be detected by the aircraft system, as the slat still deploys. If this situation continues for a prolonged periods, damage may occur in the slat system, or the other actuator may become disconnected potentially leading to a catastrophic event.
It would therefore be desirable to provide a method and apparatus by which actuator disconnection can be detected at an early stage.